My first program (Mp3 player)

Hi, I have recently started trying to teach myself python, I've watched a few video tutorials and am reading "Learning Python".
I have been making an Mp3 player and have hit a point that I cant work my way past so was hoping some kind person here could help me work it out.

The problem is I want to go from only opening one mp3 file and playing it to a playlist system but I cant work out how.

Here is my current code Using (Python 2.6 with Tkinter and mp3play).

{Edit}Just thought I should put a bit more detail in as to what I have tried so far.
basically I have tried using askopenfilenames to get the names of the files and put them in a list, but I have no idea what to do after that :(. Hope I am making some sense.